Generally, a tire with a wheel is in contact with a ground to support the load of a vehicle and absorb a shock from the ground and change a direction of the vehicle and transmit a driving force and a braking force to the ground. Today, tubeless tires are widely used for the stability in high speed driving, in which a special rubber (an inner liner) without air transmissivity is attached to an inner surface of the tire to prevent air leakage from the tire and a rim. A tire valve (a rim valve) is attached to the rim of a wheel to pump air into the tire, in which the tire valve includes a valve stem, a nut, and a valve cap.
Meanwhile, as the volume of traffic increases, a tire pressure monitoring system (TPMS) is used to increase safety in driving such that a driver in a vehicle can monitor conditions (mainly, a tire pressure and a tire temperature) of a tire. The TPMS is installed to a rim of a wheel in a tire and includes a tire pressure sensor and a tire monitor. The tire pressure sensor measures a tire pressure and then transmits a signal by wireless. The tire monitor is installed on a dashboard of a vehicle and informs a driver of conditions of the tire. At this point, the tire pressure sensor is required to be installed to the rim to measure the pressure and a temperature in the tire. However, a related art tire valve (a rim valve) is fastened in a tire and is difficult to attach a tire pressure sensor. Thus, a tire valve is required to have a structure where a tire pressure sensor is easily attached.
Particularly, as a premium trend spreads in the automobile market in recent years, inch-up wheels, the diameter of which is increased, are widely used. Such an inch-up wheel has a 2-piece or 3-piece structure to improve design. A wheel with the 3-piece structure typically includes a wheel disk, a well, and a flange, and a wheel with the 2-piece wheel includes a wheel disk and a flange.
To apply the TPMS, a tire pressure sensor valve must be installed to a wheel, but a 2-piece or 3-piece wheel employs a 17-inch or more wide tire. Since such a wide tire has a low aspect ratio ranging from 30% to 40%, a tire pressure sensor is liable to break when removing a tire bead and a rim for replacing the tire. That is, in the case of an inch-up wheel, a tire pressure sensor is installed to a rim out of a drop center of a wheel, and thus liable to collision with a tire bead.